1. Field of the Invention
The invention in general relates to steam turbine systems and in particular to a system for regulating certain corrosive depositions within the turbine system.
2. Description of the Prior Art
In a typical steam turbine system, water is transformed to superheated steam by means of a steam generator and provided to a plurality of turbine sections ranging from a high pressure section to a low pressure section. As the steam passes through the turbines, pressure and temperature changes take place such that near the exit of the low pressure turbine, the steam undergoes an expansion whereby a consequent transition to a wet condition results.
The wet steam exiting from the low pressure stage is provided to a condensor for eventual return to the steam generator. Prior to its introduction back to the steam generator, the water undergoes chemical treatment in an attempt to eliminate various impurities. Even with this water treatment, the steam passing through the turbine sections may contain impurities resulting from chemicals utilized in the water treatment, or a faulty condenser, by way of example. Although these impurities may exist at levels as slight as parts per million down to parts per billion, the deposition of these impurities on rotating steam turbine blades may lead to pitting, corrosion fatigue and stress corrosion cracking. The most common corrosive precipitates are various salts such as sodium chloride, sodium sulfate, sodium phosphate, as well as other corrosive materials such as sodium hydroxide. The present invention describes a system for reducing or eliminating the corrosive effects of corrosive salt deposition on rotating turbine blades.